The present disclosure relates to a discharging member for discharging photosensitive members, transfer sheets, fixing members and the like to be used in image forming apparatuses using an electrophotographic system, such as copiers, printers, facsimiles, and multifunction peripherals of their functions. The disclosure also relates to a charge eliminating device as well as an image forming apparatus including the discharging member.
In an image forming apparatus using electrophotographic process, electric charge remaining on a photosensitive drum (image carrier) after transfer of a toner image therefrom may cause occurrence of a memory image due to potential variations in subsequent image formation. Therefore, before execution of charging process, residual charge on the photosensitive drum is removed by a charge eliminating device, and thereafter the photosensitive drum is charged again. As a result of this, a surface of the photosensitive drum is uniformly charged, so that occurrence of memory images can be prevented. As a charge elimination method for residual charge, an optical charge elimination method for implementing charge elimination by photo-irradiation is commonly used.
However, by repetition of charge elimination by the optical charge elimination method, part of photocarriers produced inside the photosensitive layer due to light may remain or accumulate. In this case, there arises a fault of potential decreases on the surface of the photosensitive drum caused by photocarriers. Thus, there has been a desire for a charge elimination method other than the optical charge elimination method.
As a charge elimination method other than the optical charge elimination method, a noncontact charge elimination method making use of the self-discharge phenomenon has been proposed. The noncontact charge elimination method is to remove residual charge on an opposed member by making use of the self-discharge phenomenon from bump portions out of bumps and dips present on a discharging member to electrification charge present on a charge-elimination object article (discharged member). For example, there is known an image forming apparatus in which an electrically conductive part including woven fabric formed from conductive yarn is provided so as to be opposed to a recording medium placed on a conveyance path between a transfer unit and a fixing unit so that the recording medium, to which image transfer has been done by the transfer unit, is subjected to noncontact charge elimination.
Eliminating residual charge from on the surface of the photosensitive drum by using such a noncontact charge elimination method makes it unlikely that photocarriers remain inside the photosensitive layer, as would occur with the optical charge elimination method, so that decreases in the surface potential of the photosensitive drum can be suppressed. Further, since the charge eliminating roller and the photosensitive drum are out of contact with each other, there can be prevented flaws of the surface of the photosensitive drum as well as scraping of the photosensitive layer by the charge eliminating roller or contamination of the charge eliminating roller due to toner and external additives of toner sticking to the surface of the photosensitive drum. As a result, a stable charge elimination effect can be obtained over a long period.